Control for refrigerating system



April 1963 E. s. SCHLOTTERBECK 3,084,521

CONTROL FOR REFRIGERATING SYSTEM Filed March 50, 1961 2 Sheets-Sheet 1 Fig.

INVENTOR. Earl S. .Sc/r/ofierbec/r H/s Attorney A ril 9 1963 E. s. SCHLOTTERBECK 3,

CONTROL FOR REFRIGERATING SYSTEM 2 Sheets-Sheet 2 Filed March 30. 1961 giii INVENTOR. Earl 5. Sch/alierbeck His Attorney United States Patent Office 3,084,521 Patented Apr. 9, 1963 3,084,521 CONTROL FOR REFRHGERATHNG SYSTEM Earl S. Schlotterbeck, Lcwisburg, Ghio, assignor to General Motors Corporation, Detroit, Mich, a corporation of Delaware Filed Mar. 30, 1961, Ser. No. 99,606 Claims. (Cl. 62192) This invention relates to refrigerating apparatus and more particularly to a control for use in automobile air conditioning systems and the like.

It is an object of this invention to provide an improved low-cost control valve which lends itself to mass production and in which a given pressure change exerts the same influence on the valve in all positions of the valve.

Still another object of this invention is to provide a simple and inexpensive arrangement for securing a diaphragm to a valve element.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings wherein a preferred embodiment of the present invention is clearly shown.

In the drawings:

FIGURE 1 schematically shows a refrigerating system embodying the invention and shows the refrigerant throttling valve.

FIGURE 3 is a fragmentary sectional view taken substantially on line 33 of FIGURE 2.

FIGURE 4 is a fragmentary sectional view on an enlarged scale showing the diaphragm construction.

Referring now to FIGURE 1 of the drawings wherein a preferred embodiment of the invention has been shown, reference numeral designates a conventional compressor which is adapted to be driven by the car engine 1 at speeds proportional to speed of the car engine. The

compressed refrigerant flows from the compressor 10 into a condenser 12 wherein the refrigerant is liquefied before flowing through the line 14 leading to the evaporator 16. The flow of refrigerant to the evaporator is controlled by a conventional thermostatic expansion valve 18 provided with the usual sensing bulb 20: arranged in thermal exchange with the suction line 22 which leads from the outlet of the evaporator 16 to a control valve, generally designated by the reference numeral 2'4, which is arranged to control the flow of refrigerant from the evaporator 16 to the compressor 10.

The valve 24 includes a main valve body 26 which serves to guide a reciprocating valve piston 28 which is arranged to control the flow of refrigerant from the evaporator to the compressor. The upper end of the piston 28 is fastened to a rolling type diaphragm 36 by means of an integrally formed tapered boss or projection 32 which extends through an aperture 34 formed in the upper end of the piston 28. The diaphragm is of the type sometimes referred to as a rolling seal type diaphragm and rolls onto the sloping surface 33 whereby the effective area of the diaphragm increases as the opposing springs 44 and 46 are compressed. The aperture 34in the piston 28 is substantially the size of the free end of the projection 32 with the result that the free end 32 can be passed through the aperture 34 for assembly purposes and then by pulling on the end 32 the body of the member 32 will be elongated and reduced in diameter suificiently to enable one to pull the projection 32 through the aperture 34. The reexpansion which takes place in the member 32 upon release of the pulling force on the outer end thereof causes the diaphragm to be held securely to the valve piston 28.

The diaphragm 30 has its outer peripheral edge clamped between the valve body 26 and the flange 40 provided on the spring housing element 42. A pair of concentric springs 44 and 46 are arranged in the spring housing 42 and are arranged to press against a cup-shaped stamping 48 which is arranged to engage the one side of the diaphragm 30, as shown. It will be noted that the spring 44 is of such a length that it does not engage the cupshaped element 48 in the position in which the elements are shown in FIGURES '1 and 4. Upon an increase in refrigerant pressure the element 48 will contact the spring 44. A plunger element 50 serves to engage the ends of the springs 44 and 46, as shown, for the purpose of varying the amount of pres-sure exerted by the springs 44 and 46 against the diaphragm 30.

For purpose of illustration, there is shown a Bowden wire 52 which has its one end secured to a pivoted lever 54 which, in turn, is arranged to exert pressure against the plunger element 50 through the pin 56 and the adjustable stop 58. The Bowden wire 52 is preferably controlled manually from the instrument panel. Any other suitable means for adjusting the spring pressure could be substituted for the Bowden wire control. The lever '54 is pivotally mounted on a pin 60 carried by an extension 62 on the spring housing 42. A spring 64 normally biases the lever 54 in the direction which tend-s to compress the spring 46. The valve control piston 28, which is secured to the diaphragm 30, is then actuated in response to differences in pressure applied to opposite sides of the diaphragm 30. The one side of the diaphragm which abuts the'piston 28- is subjected to a pressure corresponding to the pressure within the evaporator -16. The pressure on the opposite side of the diaphragm is the sum of the pressures produced by the springs 44 and 46 and atmospheric pressure.

As shown in FIGURES -1 and 4 of the drawings, the piston 28 is provided with ports which serve to equalize the pressure at opposite ends of the piston element 28 so that the diaphragm 30 is subjected on its one side to a pressure corresponding to a pressure within the main chamber 72 formed in the valve housing 26. With the piston element 28 occupying the position in which it is shown in FIGURE 1, the flow of gas from the evaporator to the compressor is blocked thereby. A small bleed line 74 connects the bottom of the evaporator to a bypass chamber 76 formed in the valve housing 26 so as to allow lubricant trapped in the evaporator to return to the compressor through the valve housing 26 even though the valve 28 blocks the main fiow of refrigerant from the evaporator to the compressor.

A valve 75 is provided in the line 74 and serve to prevent flow through the line 74 when refrigeration is called for and the expansion valve 18 is open. When the expansion valve 18 closes and the compressor continues to operate even though no appreciable refrigerant is being returned to the compressor from the evaporator, the pressure d-iiferential on the valve 75 changes and causes the valve 75 to open and thereby allow any lubricant trapped in the evaporator to return to the compressor even though the valve element 28 has closed the connection between the compressor inlet and the evaporator outlet. This arrangement is especially advantageous in systems operating with a reduced refrigerant charge resu-lting fnom a leak in the refrigerant lines.

A conventional equalizing line 79 for the expansion valve 18 is also provided as shown and functions in its 'usual manner to adjust for the pressure drop through the evaporator. It will be noted, however, that the line 79 leads to the bypass chamber 76 of the valve housing 26 whereby the continued operation of the compressor after the valve element 28 has closed the outlet line 22 causes the pressure in the line '79 to decrease to a point where the expansion valve 18 will momentarily reopen to allow a sufficient amount of refrigerant to enter the evaporator so as to momentarily reopen the valve 28. This then results in some return of lubricant and refrigerant to the compressor at repeated intervals even though no refrig-.

eration is required.

.While the embodiment of the present invention as herein disclosed constitutes a preferred form, it is to be understood that other forms might be adopted.

What is claimed is as follows:

1. In a refrigerating system; a compressor, a condenser; an evaporator; refrigerant flow means connecting H said compressor, condenser and evaporator in series refrigerant flow relationship; said flow means including an expansion valve at the inlet to saidevaporator and a throttling valve at the outlet of said evaporator; said throttling valve including a valve body having a plurality of refrigerant inlets and a refrigerant outlet; 2. first of said inlets being connected to the outlet of said evaporator; a second of said inlets being connected to the bottom of said evaporator for returning lubricant from the bottom of said evaporator to said valve body; said outlet being connected to said compressor; a diaphragm carried by said valve body and having one side subjected to refrigerant pressure in said valve body; a flow control element arranged to be actuated by said diaphragm and having means to block the flow from the first of said inlets to said outlet without blocking the flow from the second of said inlets to said outlet; said flow control element having an aperture formed therein; said diaphragm having an integrally formed projection extending through said aperture; said projection comprising a yieldable element slightly larger than said aperture whereby said flow control element is secured to said diaphragm.

2. In a refrigerating system; a compressor; a condenser; an evaporator; refrigerant flow means connecting said compressor, condenser and evaporator in series refrigerant flow relationship; said flow means including an expansion valve at the inlet to said evaporator and a throttling valve at the outlet of said evaporator; said throttling valve including a valve body having a plurality of refrigerant inlets and a refrigerant outlet; a first of said inlets being connected to the outlet of said evaporator; a second of said inlets being connected to the bottom of said evaporator for returning lubricant from the bottom of said evaporator to said compressor; said outlet being connected to said compressor; a diaphragm carried by said valve body and having one side subjected to refrigerant pressure in said valve body; a fiow control element arranged to be actuated by said diaphragm and having means to block the flow from the first of said inlets to said outlet without blocking the flow from the second of said inlets to said outlet; said flow control element having an aperture formed therein; said diaphragm having an integrally formed projection extending through said aperture; said projection comprising a yieldable element slightly larger than said aperture whereby said flow control element is secured to said diaphragm; said valve body having a bypass chamber surrounding said flow control element and serving at all times to connect said second inlet to said outlet.

. 3. A valve operating mechanism actuated by fluid pressure comprising a hollow casing having an opening in a body portion thereof, a valve actuating member, a flexible diaphragm extending across said opening and secured at its periphery to said casing, a diaphragm follower in said casing positioned to engage one side of said diaphragm and having a cross-sectional area less than that of said opening, a spring operatively pressing against said follower to exert pressure on one side of said diaphragm, an integral projection formed on said diaphragm and having a wedging engagement within an aperture in said valve actuating member so as to secure said diaphragm to said valve actuating member, said casing providing a surface extending around said opening and sloping outwardly from the opening in a direction away from said follower, said flexible diaphragm having an annular looping fold extend-ing into the space between said follower and said sloping surface whereby upon axial movement of the diaphragm the effective area of the diaphragm is varied, said diaphragm having a surface exposed to fluid pressure in opposition to the pressure exerted by said spring, said effective area increasing and decreasing as the pressure of the spring increases and decreases whereby the valve operating mechanism actuates a valve in accordance with the fluid pressure applied to said diaphragm.

4. A valve operating mechanism actuated by fluid pres-t sure comprising a hollow casing having an opening in a body portion thereof, a flexible diaphragm extending across said opening and secured at its periphery to said casing, said diaphragm having an integrally formed resilient projection on its one side, a valve actuator element having an aperture smaller than said projection through which said projection extends, a diaphragm follower positioned to engage the other side of said diaphragm and having a cross-sectional area less than that of said opening, a spring operatively pressing against said follower to exert pressure on said diaphragm, said casing providing a surface extending around said opening and sloping outwardly from the opening in a direction away from said follower, said flexible diaphragm having an annular looping fold extending into the space between said follower and said sloping surface whereby upon axial movement of the diaphragm the effective area of the diaphragm is varied, said diaphragm having a surface exposed to fluid pressure in opposition to the pressure exerted by said spring, said effective area increasing and decreasing as the pressure of the spring increases and decreases whereby the valve operating mechanism actuates a valve in accordance with the fluid pressure applied to said diaphragm.

5. In a refrigerating system; a compressor; a condenser; an evaporator; refrigerant fiow means connecting said compressor, condenser and evaporator in series refrigerant flow relationship; said refrigerant flow means including an expansion valve at the inlet to said evaporator and a throttling valve at the outlet of said evaporator; said throttling valve including a valve body having a cavity therein and having a plurality of refrigerant inlets and a refrigerant outlet, a first of said inlets being connected to the outlet of said evaporator; a second of said inlets being connected to the bottom of said evaporator for returning lubricant fromthe bottom of said evaporator to said valve body; said outlet being connected to said compressor; a diaphragm carried by said valve body in said cavity and having one side subjected to refrigerant pressure in said valve body; a flow control element arranged to be actuated by said diaphragm and having means to block the flow from the first of said inlets to said outlet without blocking the flow from the second of said inlets to said outlet; a diaphragm follower positioned to engage one side of said diaphragm and having a cross-sectional area less than that of said cavity, a spring operatively pressing against said follower to exert pressure on said diaphragm, said valve body providing a surface extending around said cavity and sloping outwardly from the flow control element in a direction away from References Cited in the file of this patent UNITED STATES PATENTS Terry Dec. 12, 1933 McKee Sept. 11, 1951 Sutton Sept. 16, 1952 Seljos Mar. 4, 1958 Mitchell Dec. 27, 1960 

5. IN A REFRIGERATING SYSTEM; A COMPRESSOR; A CONDENSER; AN EVAPORATOR; REFRIGERANT FLOW MEANS CONNECTING SAID COMPRESSOR, CONDENSER AND EVAPORATOR IN SERIES REFRIGERANT FLOW RELATIONSHIP; SAID REFRIGERANT FLOW MEANS INCLUDING AN EXPANSION VALVE AT THE INLET TO SAID EVAPORATOR AND A THROTTLING VALVE AT THE OUTLET OF SAID EVAPORATOR; SAID THROTTLING VALVE INCLUDING A VALVE BODY HAVING A CAVITY THEREIN AND HAVING A PLURALITY OF REFRIGERANT INLETS AND A REFRIGERANT OUTLET, A FIRST OF SAID INLETS BEING CONNECTED TO THE OUTLET OF SAID EVAPORATOR; A SECOND OF SAID INLETS BEING CONNECTED TO THE BOTTOM OF SAID EVAPORATOR FOR RETURNING LUBRICANT FROM THE BOTTOM OF SAID EVAPORATOR TO SAID VALVE BODY; SAID OUTLET BEING CONNECTED TO SAID COMPRESSOR; A DIAPHRAGM CARRIED BY SAID VALVE BODY IN SAID CAVITY AND HAVING ONE SIDE SUBJECTED TO REFRIGERANT PRESSURE IN SAID VALVE BODY; A FLOW CONTROL ELEMENT ARRANGED TO BE ACTUATED BY SAID DIAPHRAGM AND HAVING MEANS TO BLOCK THE FLOW FROM THE FIRST OF SAID INLETS TO SAID OUTLET WITHOUT BLOCKING THE FLOW FROM THE SECOND OF SAID INLETS TO SAID OUTLET; A DIAPHRAGM FOLLOWER POSITIONED TO ENGAGE ONE SIDE OF SAID DIAPHRAGM AND HAVING A CROSS-SECTIONAL AREA LESS THAN THAT OF SAID CAVITY, A SPRING OPERATIVELY PRESSING AGAINST SAID FOLLOWER TO EXERT PRESSURE ON SAID DIAPHRAGM, SAID VALVE BODY PROVIDING A SURFACE EXTENDING AROUND SAID CAVITY AND SLOPING OUTWARDLY FROM THE FLOW CONTROL ELEMENT IN A DIRECTION AWAY FROM SAID FOLLOWER, SAID FLEXIBLE DIAPHRAGM HAVING AN ANNULAR LOOPING FOLD EXTENDING INTO THE SPACE BETWEEN SAID FOLLOWER AND SAID SLOPING SURFACE WHEREBY UPON AXIAL MOVEMENT OF THE DIAPHRAGM HAVING A SURFACE EXPOSED TO FLUID PRESSURE IN OPPOSITION TO THE PRESSURE EXERTED BY SAID SPRING, SAID EFFECTIVE AREA INCREASING AND DECREASING AS THE PRESSURE OF SAID SPRING INCREASES AND DECREASES WHEREBY THE FLOW CONTROL ELEMENT IS ACTUATED IN ACCORDANCE WITH THE FLUID PRESSURE APPLIED TO SAID DIAPHRAGM. 